MAPT and early-onset autosomal dominant Alzheimer disease: This includes genes involved in the production or modification of β-amyloid or tau, which form amyloid plaques and neurofibrillary tangles seen in Alzheimer’s disease brains [136] as well as genes involved in regulating the expression and aberrant accumulation of α-synuclein, a pathological feature of Parkinson’s disease [137,138].